Device and Method for Assisting Selection of Surgical Staple Height

ABSTRACT

A compression gauge cartridge for use mounted in a cartridge bay of a cartridge jaw member of a surgical stapler instrument to compress a tissue consistently to a predetermined thickness and measure a reactionary load therefrom comprises: a cartridge body; a force gauge assembly comprising a force transducer and a compression head having a tissue compression ace, wherein the force gauge assembly is supported by the cartridge body, and wherein the compression head is configured and disposed so that the tissue compression face thereof lies substantially closer to the tissue contacting surface of the anvil jaw member than the tissue supporting surface of the cartridge body; and a spacer member extending from the tissue supporting surface of the cartridge body, wherein the force gauge assembly is positioned distally with respect to the spacer member.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation application which claims thebenefit of and priority to U.S. patent application Ser. No. 15/893,638,filed Feb. 11, 2018, the entire contents of which are incorporated byreference.

TECHNICAL FIELD

The present invention relates to a medical device and method for use insurgical procedures. More particularly, the present invention relates toa surgical device and method for assisting selection of surgical stapleheight in a surgical stapling operation.

BACKGROUND OF THE INVENTION

The utilization of mechanical tissue fastening instruments, notably,open and endoscopic surgical staplers have been increasing steadily inrecent years as a substitute for suturing in joining a tissue, joiningand cutting a tissue simultaneously and performing anastomosis oftubular organs belonging to the digestive system in a number of surgicaldisciplines. Over the years these instruments have proven to providesignificant clinical benefits of improved patient outcome in addition toprocedural benefits of reduced procedure time and simplified surgicaltasks when compared to laborious and time consuming suturing, andrelated cost savings. In certain types of surgical procedures use ofsurgical staplers has become the preferred method of joining a tissueincluding the bariatric, thoracic and colorectal surgeries.

There are several known types of surgical stapler instrumentsspecifically adapted for use in various procedures such as end-to-endanastomosis, gastrointestinal anastomosis, endoscopic gastrointestinalanastomosis, and transverse anastomosis. Examples of stapler instrumentsfor these various procedures can be found in U.S. Pat. Nos. 5,915,616;6,202,914; 5,865,361; and 5,964,394, which are each herein incorporatedby reference.

Known endoscopic surgical stapler instruments comprise a handle and anend effector that are fixedly attached to either ends of an elongateshaft and operatively engaged with each other. An end effectorsimultaneously makes a longitudinal incision in tissue and applies linesof staples on opposing sides of the incision. An end effector includes apair of opposed jaw members that, if the instrument is intended forendoscopic or laparoscopic applications, are capable of passing througha cannula passageway. One of the jaw members, often referred to as acartridge jaw member, receives a staple cartridge having at least twolaterally spaced rows of staples in an elongate cartridge channel or acartridge bay. The other jaw member, often referred to as an anvil jawmember, defines an anvil having staple-forming pockets aligned with therows of staples in the staple cartridge. The instrument commonlyincludes a plurality of reciprocating wedges which, when drivendistally, pass through openings in the staple cartridge and engagedrivers supporting the staples to effect the firing of the staplestoward the anvil.

In surgical stapling operation a physician operator first positions theend effector of a surgical stapler instrument to capture a target tissuebetween the two jaw members in open position and then operates thehandle to close the two jaw members to clamp and compress the targettissue to a nominal thickness defined by the gap distance between thetissue contacting surfaces of the staple cartridge and the anvil priorto the firing of the staples. In the designs of presently availablestapler instruments a physician has no means to control the degree orforce of target tissue compression but is presented with a set ofstandardized staple cartridges colored coded according to the formedheight(s) of staples contained therein, which correlates with the gapdistance between the tissue contacting surfaces of the stale cartridgeand anvil. Presently, the standardized set of staple cartridges,typically color coded white, blue, gold, green and black in theascending order of staple heights contained therein, includes stapleswith formed heights between 1 mm and 2.3 mm in discrete increment. Thereare also in the market a set of staple cartridges, each cartridgecontaining a combination staples of varying heights with its own uniquecolor coding tailored for application on tissue with varying compressedthickness. In compressing the target tissue the two jaw memberscomprising the end effector of stapler instrument are subject to adistributed reactionary load from the compressed tissue usuallyresulting in deflection of the two jaw members increasing progressivelyalong the length thereof going from the proximal to distal end and moreso, in the anvil than in the cartridge jaw member which is moresubstantial and structurally rigid. The corresponding variation in thegap distance between the tissue contacting surfaces of the staplecartridge and the anvil makes the tissue compression non-uniformdecreasing progressively going from the proximal to distal ends of theend effector.

The level of tissue compression is one of the key factors that determinesuccess of a surgical stapling operation often defined by adequatehemostasis and minimal damage of tissue along the staple line, andleak-free sealing of the target tubular organ among otherconsiderations. It is known that a desirable clinical outcome of asurgical stapling operation is most likely achieved when the targettissue is compressed to a compression force between 6 g/mm² or 8 g/mm².Since present surgical stapler technology does not provide means tocontrol the compression force of the target tissue a physician needs tochoose a staple cartridge out of a standard set that would bestapproximate the optimal compression force for the target tissue when thetwo jaw members are closed with the chosen staple cartridge mounted inthe cartridge bay. Having no practical means to help direct selection ofstaple cartridge, for example, accessory tools to directly assess a keymechanical property or condition of the target tissue, a physician isleft to rely solely on his or her experience, or educated guess inselecting a staple cartridge, which leaves open possibility of under- orover-compression of the target tissue. Under-compression of tissue couldlead to inadequate hemostasis and potential leakage of content containedwithin the tissue while over-compression to tearing of tissue orischemia requiring prolonged period of healing. The staple cartridgeselection is particularly difficult for a target tissue belonging to anorgan with naturally occurring, large thickness variation such as in thestomach or an organ with unknown variation in mechanical properties suchas in the lung at different disease state.

Manufacturers of present surgical stapler instruments instruct aphysician to verify the adequacy of selected staple cartridge incompressing a target tissue by the feedback force felt in the handoperating the handle of the stapler instrument to apply the tissuecompression. The instructions basically say to switch to a new staplecartridge with staples of larger formed height if it is overly difficultto operate the handle to apply compression to the target tissuespecifically to guard against over-compression. This method is proven tobe hardly practical in the field because the feedback force felt in thepalm of the physician's hand may not necessarily correlates with thelevel of tissue compression due to the facts that the feedback force maybe distorted being passed down through mechanical linkages and jointscomprising the operating mechanism for the end effector and that the twojaw members comprising the end effector undergoes deflection caused bythe reactionary load from the compressed tissue. In addition a unit ofchange in the compressed tissue thickness represented by the standardset of staple cartridges typically corresponds to only around few tensof gram of force in tissue compression which is barely discernible bythe haptic sense felt in the palm of the hand alone even under the bestof circumstances. Corresponding instruction for staple cartridgeselection for preventing under-compression of a target tissue does noteven exist.

U.S. Pat. No. 8,893,946 to Boudreaux et al., which is hereinincorporated by reference, describes a surgical instrument that includescomponents for measuring the thickness of a tissue clamped between thetwo jaw members of an end effector thereof relying on a strain gauge orstrain gauges as a means to generate a signal or signals correspondingto the tissue thickness and/or a compression load applied to the tissue.This disclosure describes the strain gauges as being used stand-alonebut fails to describe how the strain gauges are practically implemented,for example, in the form of a load cell, well known to those of skill inthe art, to generate such signals that could be converted to thethickness of tissue or the compression load acting thereon. The surgicalinstrument in this disclosure does not include any means to prevent orcompensate for the potential deflection of a jaw member comprising anend effector as a result of a reactionary load from the compressedtissue nor for the effect of the play present in the closure mechanismof the two jaw members comprising the end effector on the tissuethickness measurement. This disclosure also fails to define thethickness of the clamped tissue in such sufficient detail for it to beof practical use in the selection of a staple cartridge for a staplingoperation on the tissue.

Therefore, significant needs exist for a surgical device and method thatwould aid a physician in selecting a staple cartridge from the standardset of staple cartridges.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed toward a surgical device and methodfor use in surgical procedures. More particularly, the present inventionrelates to a surgical device and method for assisting selection of astaple cartridge from the standard set of staple cartridges optimal fora target tissue of a surgical stapling operation.

To address the foregoing needs and with other objects in view there areprovided, in accordance with the present invention, a surgical devicefor enabling a surgical stapler instrument to compress a tissueconsistently to a predetermined thickness and measure a reactionary loadtherefrom and a method for assisting a physician in selecting a staplecartridge optimal for a tissue of a surgical stapling operation.

In a preferred embodiment of the present invention, a compression gaugecartridge for use mounted in a cartridge bay of a cartridge jaw membercomprising an end effector, together with an anvil jaw member having atissue contacting surface, of a surgical stapler instrument to compressa tissue consistently to a predetermined thickness and measure areactionary load therefrom for assisting selection of a staple cartridgeand assessing a condition of a tissue comprises: a cartridge body havinga proximal end and a distal end, and a tissue supporting surface,wherein said cartridge body is configured for said compression gaugecartridge to be releasably mounted in said cartridge bay and for saidtissue supporting surface to be at least at a predetermined distancefrom said tissue contacting surface of said anvil jaw member when saidcartridge jaw member and said anvil jaw member are in a fully closedposition; a force gauge assembly comprising a force transducer and acompression head having a tissue compression face, wherein said forcegauge assembly is supported by said cartridge body positioned betweensaid proximal end and said distal end thereof and wherein saidcompression head is configured and disposed so that said tissuecompression face thereof lies substantially closer to said tissuecontacting surface of said anvil jaw member than said tissue supportingsurface of said cartridge body; and a spacer member extending from saidtissue supporting surface of said cartridge body, wherein saidcompression head comprising said force gauge assembly is positioneddistally with respect to said spacer member. In an alternate embodimentsaid tissue supporting surface of said cartridge body may be contouredin such a way to further reduce compression of said tissue disposedbetween said tissue supporting surface and said tissue contactingsurface when said cartridge jaw member and said anvil jaw member are ina fully closed position.

In an alternate embodiment of the present invention, a compression gaugecartridge for use mounted in a cartridge bay of a cartridge jaw membercomprising an end effector, together with an anvil jaw member having atissue contacting surface, of a surgical stapler instrument to compressa tissue so that said cartridge jaw member and said anvil jaw membercome to a predetermined angular positional relationship with each otherand measure a reactionary load therefrom for assisting selection of astaple cartridge comprises: a cartridge body having a proximal end and adistal end, and a tissue supporting surface, wherein said cartridge bodyis configured for said compression gauge cartridge to be releasablymounted in said cartridge bay and for said tissue supporting surface tobe at least at a predetermined distance from said tissue contactingsurface of said anvil jaw member when said cartridge jaw member and saidanvil jaw member are in a fully closed position; and a force gaugeassembly comprising a force transducer and a compression head having atissue compression face, wherein said force gauge assembly is supportedby said cartridge body positioned between said proximal end and saiddistal end thereof and wherein said compression head is configured anddisposed so that said tissue compression face thereof lies substantiallycloser to said tissue contacting surface of said anvil jaw member thansaid tissue supporting surface of said cartridge body. In an alternateembodiment said tissue supporting surface of said cartridge body may becontoured in such a way to further reduce compression of said tissuedisposed between said tissue supporting surface and said tissuecontacting surface when said cartridge jaw member and said anvil jawmember are in a fully closed position.

In an embodiment of the present invention, a surgical stapler instrumentmay further include a spacer block of a predetermined height disposed ata handle comprising said surgical stapler instrument for defining apredetermined extent said handle may be operated to close a cartridgejaw member and an anvil jaw member comprising an end effector comprisingsaid surgical stapler instrument so that said cartridge jaw member andsaid anvil jaw member come to a predetermined angular positionalrelationship with each other.

In a preferred embodiment of the present invention, a surgicalcompression gauge instrument for compressing a tissue consistently to apredetermined thickness and measuring a reactionary load therefrom forassisting selection of a staple cartridge and assessing a condition of atissue comprises: a handle portion; a body portion extending distallyfrom said handle portion and defining a longitudinal axis; and a toolassembly disposed at a distal end of and operatively connected to saidbody portion, and comprising a compression gauge jaw member having aproximal end and a distal end and a tissue supporting surface, and ananvil jaw member having a tissue contacting surface, wherein saidcompression gauge jaw is configured for said tissue supporting surfacethereof to be at least at a predetermined distance from said tissuecontacting surface of said anvil jaw member when said compression gaugejaw member and said anvil jaw member are in a fully closed position, andconfigured to open and close when operated by said handle portion,wherein said compression gauge jaw member comprises a force gaugeassembly, supported therein and positioned between said proximal end andsaid distal end thereof, comprising a force transducer and a compressionhead having a tissue compression face, wherein said compression head isconfigured and disposed so that said tissue compression face thereoflies substantially closer to said tissue contacting surface of saidanvil jaw member than said tissue supporting surface of said compressiongauge jaw member; and a spacer member extending from said tissuesupporting surface of said compression gauge jaw member, wherein saidcompression head comprising said force gauge assembly is positioneddistally with respect to said spacer member.

In a preferred embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a predeterminedcartridge from the set of standard staple cartridges, between a tissuecompression face of a compression head comprising a force gauge assemblycomprising said compression gauge cartridge and a tissue contactingsurface of said anvil jaw member; capturing a tissue between saidcartridge jaw member and said anvil jaw member; closing said cartridgejaw member and said anvil jaw member to compress said tissue capturedbetween said tissue compression face and said tissue contacting surfaceto a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; comparing saidreactionary load reading with a value known to be optimal for a staplingoperation of said tissue to determine if said reactionary load is case(1) within, case (2) below or case (3) above a window of a predeterminedwidth around said optimal value and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height corresponding to saidpredetermined thickness of said compressed tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (2), or a staple cartridge containing staples of aheight larger than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (3). In an alternate embodiment, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation may further comprise a step of waitingfor a predetermined length of time after closing said cartridge jawmember and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined average height, optimal for atissue of a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to an average height of staples contained in apredetermined cartridge from the set of standard staple cartridges,between a tissue compression face of a compression head comprising aforce gauge assembly comprising said compression gauge cartridge and atissue contacting surface of said anvil jaw member; capturing a tissuebetween said cartridge jaw member and said anvil jaw member; closingsaid cartridge jaw member and said anvil jaw member to compress saidtissue captured between said tissue compression face and said tissuecontacting surface to a predetermined thickness corresponding to saidgap distance there-between; reading out a reactionary load from saidcompressed tissue displayed on a force transducer indicator; comparingsaid reactionary load reading with a value known to be optimal for astapling operation of said tissue to determine if said reactionary loadis case (1) within, case (2) below or case (3) above a window of apredetermined width around said optimal value and how large a size ofdifference is in cases (2) and (3); selecting a staple cartridge fromsaid standard set of staple cartridges containing staples of an averageheight corresponding to said predetermined thickness of said compressedtissue if the result of comparison is case (1), or a staple cartridgecontaining staples of an average height smaller than said predeterminedthickness of said compressed tissue taking into account said size ofdifference if the result of comparison is case (2), or a staplecartridge containing staples of an average height larger than saidpredetermined thickness of said compressed tissue taking into accountsaid size of difference if the result of comparison is case (3). In analternate embodiment, a method for selecting a staple cartridge from thestandard set of staple cartridges, each containing staples of apredetermined average height, optimal for a tissue of a surgicalstapling operation may further comprise a step of waiting for apredetermined length of time after closing said cartridge jaw member andsaid anvil jaw member to compress said tissue.

In another alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a green cartridge fromthe set of standard staple cartridges, between a tissue compression faceof a compression head comprising a force gauge assembly comprising saidcompression gauge cartridge and a tissue contacting surface of saidanvil jaw member; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured between said tissuecompression face and said tissue contacting surface to a predeterminedthickness corresponding to said gap distance there-between; reading outa reactionary load from said compressed tissue displayed on a forcetransducer indicator; comparing said reactionary load reading with avalue known to be optimal for a stapling operation of said tissue todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said optimalvalue; selecting a green cartridge from the standard set of staplecartridges if the result of comparison is case (1) or a blue cartridgeif the result of comparison is case (2), or a black cartridge if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance between atissue compression face of a compression head comprising a force gaugeassembly comprising said compression gauge cartridge and a tissuecontacting surface of said anvil jaw member; capturing a tissue betweensaid cartridge jaw member and said anvil jaw member; closing saidcartridge jaw member and said anvil jaw member to compress said tissuecaptured between said tissue compression face and said tissue contactingsurface to a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; providing a referencetissue for which an optimal staple height for a surgical staplingoperation is known; comparing said reactionary load reading with areactionary load from said reference tissue compressed to saidpredetermined thickness over the same area of said reference tissue asthat of said tissue compression face of said compression head todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said reactionaryload from said reference tissue and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height known to be optimal forsaid reference tissue if the result of comparison is case (1), or astaple cartridge containing staples of a height smaller than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (2),or a staple cartridge containing staples of a height larger than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (3).In an alternate embodiment, a method for selecting a staple cartridgefrom the standard set of staple cartridges, each containing staples of apredetermined height, optimal for a tissue of a surgical staplingoperation may further comprise a step of waiting for a predeterminedlength of time after closing said cartridge jaw member and said anviljaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member having a tissue contacting surface, of a surgicalstapler instrument; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured there-between so thatsaid cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other; readingout a reactionary load from said compressed tissue displayed on a forcetransducer indicator; providing a reference tissue for which an optimalstaple height for a surgical stapling operation is known; comparing saidreactionary load reading with a reactionary load from said referencetissue compressed so that said cartridge jaw member and said anvil jawmember come to said predetermined angular positional relationship witheach other to determine if said reactionary load is case (1) within,case (2) below or case (3) above a window of a predetermined widtharound said reactionary load from said reference tissue and how large asize of difference is in cases (2) and (3); selecting a staple cartridgefrom the standard set of staple cartridges containing staples of aheight known to be optimal for said reference tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than that of staples known to be optimal for saidreference tissue taking into account said size of difference if theresult of comparison is case (2), or a staple cartridge containingstaples of a height larger than that of staples known to be optimal forsaid reference tissue taking into account said size of difference if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In order to make an informed selection of a staple cartridge for atissue of a surgical stapling operation or to assess a condition of atissue in a surgery, a physician mounts a compression gauge cartridge ofthe present invention in a cartridge bay of a cartridge jaw member of asurgical stapler instrument prepared to be used for the staplingoperation or employ a dedicated surgical instrument with a toolassembly, a jaw member of which is instrumented with a compression gaugedevice including a force gauge assembly and a spacer member. Thephysician then operates the handle portion of the surgical staplerinstrument or the dedicated surgical instrument to capture a tissuebetween the two jaw members comprising the end effector or a toolassembly and close the two jaw members to compress the tissue to apredetermined thickness set by the spacer member comprising thecompression gauge cartridge or the compression gauge device. Thesurgical stapler instrument instrumented with the compression gaugecartridge and the dedicated surgical instrument instrumented with thecompression gauge device is capable of providing a predetermined gapdistance consistently and with a high degree of repeatability betweenthe tissue compression face of the compression head comprising the forcegauge assembly and the tissue contacting surface of the anvil jawmember. The compression of tissue takes place over the area covered bythe tissue compression face of the compression head, which reduces thetissue to a predetermined thickness corresponding to the predeterminedgap distance. Preferably, the predetermined thickness of the compressedtissue is the formed height of staples contained in a green staplecartridge from the standard set of staple cartridges. The compressionhead transfer a reactionary load from the compressed tissue exertedthereon to the force transducer comprising the force gauge assembly,which is displayed on a force transducer indicator connected to theforce transducer comprising the force gauge assembly. Comparing thereactionary load with a known optimal tissue compression force for asurgical stapling operation the physician may decide to choose a greenstaple cartridge or other staple cartridges, blue or black, containingstaples of a height smaller or larger than the green cartridge in thestandard set of staple cartridges. Preferably, the control program forthe force transducer indicator includes a software function forperforming the comparison of the measured reactionary load with a set ofvalues stored in the internal memory to provide a signal indicating arecommendation on the staple cartridge selection, for example, in theform of a color coded signal lights or other easily recognizable forms.

The presently disclosed compression gauge cartridge and method, togetherwith attendant advantages, will be more clearly illustrated below by thedescription of the drawings and the detailed description of theembodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The following exemplary figures are provided to supplement thedescription below and more clearly describe the invention. In thefigures, like elements are generally designated with the same referencenumeral for illustrative convenience and should not be used to limit thescope of the present invention.

FIG. 1 is a plot of a stress-strain curve of a stomach tissue accordingto an embodiment of the present invention.

FIG. 2A is a perspective view of an exemplary surgical staplerinstrument according to an embodiment of the present invention.

FIG. 2B is a perspective view of an end effector of an exemplarysurgical stapler instrument according to an embodiment of the presentinvention.

FIG. 3A is a perspective view of a compression gauge cartridge disposedin a cartridge bay of a cartridge jaw member of an end effector of anexemplary surgical stapler instrument according to an embodiment of thepresent invention.

FIG. 3B is a perspective view of a compression gauge cartridgepositioned spaced apart from a cartridge bay according to an embodimentof the present invention.

FIG. 3C is an exploded view of a compression gauge cartridge accordingto an embodiment of the present invention.

FIG. 3D is a perspective view of a compression gauge cartridge with acartridge body sectioned along the line 3D-3D shown in FIG. 3C andspaced apart according to an embodiment of the present invention.

FIG. 4A is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 4B is a perspective view of a compression gauge cartridge, shown inFIG. 4A, with a cartridge body sectioned similarly to that shown in FIG.3C and spaced apart according to an alternate embodiment of the presentinvention.

FIG. 5A is a perspective view of a compression gauge cartridge accordingto another alternate embodiment of the present invention.

FIG. 5B is a perspective view of a compression gauge cartridge, shown inFIG. 5A, with a cartridge body sectioned similarly to that shown in FIG.3C and spaced apart according to another alternate embodiment of thepresent invention.

FIG. 6A is a schematic, side elevation view of a tissue captured betweenan anvil jaw member and a staple cartridge comprising a cartridge jawmember in an open position according to an embodiment of the presentinvention.

FIG. 6B is a schematic, side elevation view of a tissue compressedbetween an anvil jaw member and a staple cartridge in a closed positionaccording to an embodiment of the present invention.

FIG. 6C is a perspective view of a cartridge body comprising acompression gauge cartridge according to an embodiment of the presentinvention.

FIG. 6D is a schematic, side elevation view of a tissue compressedbetween a compression gauge cartridge comprising a cartridge jaw memberand an anvil jaw member in a closed position according to an embodimentof the present invention.

FIG. 6E is a perspective view of a cartridge body comprising acompression gauge cartridge according to an alternate embodiment of thepresent invention.

FIG. 7A is a perspective view of a force gauge assembly with acompression head set spaced apart according to an embodiment of thepresent invention.

FIG. 7B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a long symmetry plane and spaced apartaccording to an alternate embodiment of the present invention.

FIG. 7C is a perspective view of a signal conduction means and acartridge jaw member partially broken away according to an embodiment ofthe present invention.

FIG. 7D is a perspective view of a signal conduction means comprising acompression gauge cartridge partially broken away according to analternate embodiment of the present invention.

FIG. 8A is a perspective view of a force gauge assembly with acompression head set spaced apart therefrom according to an alternateembodiment of the present invention.

FIG. 8B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a long symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 8C is a perspective view of a cantilevered compression headcomprising a force gauge assembly disposed in a cartridge body shownpartially broken away, sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 8D is a perspective view of a deformable compression headcomprising a force gauge assembly disposed in a cartridge body shownpartially broken away, sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIG. 9A is a perspective view of a force gauge assembly with acompression head set spaced apart therefrom according to anotheralternate embodiment of the present invention.

FIG. 9B is a perspective view of a compression head comprising a forcegauge assembly sectioned along a symmetry plane and spaced apartaccording to an another alternate embodiment of the present invention.

FIGS. 10A and 10B are side elevation views of a compression gaugecartridge comprising a cartridge jaw member and an anvil jaw memberaccording to embodiments of the present invention.

FIG. 11A is a perspective view of a cartridge body and a repositionablespacer member comprising a compression gauge cartridge according to anembodiment of the present invention.

FIGS. 11B and 11C are perspective views of a spacer member with anextension member according to embodiments of the present invention.

FIG. 11D is a perspective view of a protective cover disposed on acartridge body comprising a compression gauge cartridge according to anembodiment of the present invention.

FIGS. 12A-12C are perspective views of a cartridge body and a cartridgebay, partially broken away and sectioned and spaced apart, and anadjustable spacer member comprising a compression gauge cartridgeaccording to various embodiments of the present invention.

FIGS. 12D and 12E are perspective views of a cartridge body and acartridge bay, partially broken away and sectioned and spaced apart, anda rotatable spacer member comprising a compression gauge cartridgeaccording to an alternate embodiment of the present invention.

FIG. 13A is a schematic, side elevation view of a reference block, acompression gauge cartridge and an anvil jaw member according to anembodiment of the present invention.

FIG. 13B is a perspective view of a protective cover disposed on acartridge body according to an embodiment of the present invention.

FIG. 13C is a perspective view of a cartridge body, a protective coverand a cartridge bay, partially broken away and sectioned and spacedapart, and an adjustable spacer member biased by a spring according toan embodiment of the present invention.

FIG. 14 is an assembly view of a compression gauge cartridge comprisingtwo parts according to an alternate embodiment of the present invention.

FIG. 15 is a perspective view of a surgical compression gauge instrumentcomprising a compression gauge jaw member according to an embodiment ofthe present invention.

FIG. 16 is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 17 is a side elevation view of a compression gauge cartridgecomprising a cartridge jaw member and an anvil jaw member according toembodiments of the present invention.

FIG. 18 is a perspective view of a surgical stapler instrument accordingto an embodiment of the present invention.

FIG. 19 is a perspective view of a compression gauge cartridge accordingto an alternate embodiment of the present invention.

FIG. 20 is a perspective view of a compression gauge cartridge with acartridge body sectioned similarly to that shown in FIG. 3C and spacedapart according to an alternate embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The novel features of the present invention will become apparent tothose of skill in the art upon examination of the following detaileddescription of the invention. It should be understood, however, that thedetailed description of the invention and the specific examplespresented, while indicating certain embodiments of the presentinvention, are provided for illustration purposes only because variouschanges and modifications within the spirit and scope of the inventionwill become apparent to those of skill in the art from the detaileddescription of the invention and claims that follow.

Embodiments of the presently disclosed surgical device will now bedescribed in detail with reference to the drawing figures wherein likereference numerals identify similar or identical elements. In thedrawings and in the description which follows, the term “proximal”, asis traditional, will refer to the end of the surgical device which isclosest to a physician while the term “distal” will refer to the end ofthe device which is furthest from a physician. However, surgicalinstruments are used in many orientations and positions, and these termsare not intended to be limiting and absolute. The terms “force”, “load”,and “force load” may be used interchangeably herein to describe variousmechanical forces including a reaction thereto. It should be appreciatedthat spatial terms such as vertical, horizontal, right, left or above,etc., are given herein with reference to the figures. In actualpractice, however, a surgical device or instrument may be oriented atvarious angles and, as such, these spatial terms are used relative tothe surgical device or instrument.

The present invention relates to a surgical device and method for use ina surgical procedure. More particularly, the present invention relatesto a surgical device for enabling compression of a tissue consistentlyto a predetermined thickness with a high degree of repeatability andmeasurement of a reactionary load from the compressed tissue to assistin the selection of a staple cartridge from the standard set of staplecartridges optimal for the tissue of a surgical stapling operation andto assess a condition of a tissue of a surgical operation in a surgicalprocedure. In an embodiment a surgical device of the present inventionmay be advantageously adapted for use, as an add-on accessory, mountedin a cartridge bay comprising a cartridge jaw member of an end effectorof an endoscopic surgical stapler instrument. A surgical device of thepresent invention may be configured to include retention featuressimilar to a staple cartridge for releasably mounting in an opencartridge bay, if available in a surgical stapler instrument, orotherwise fixedly integrated with a cartridge jaw member of a disposablereload unit found in certain surgical stapler instruments in the market.Advantages of a surgical device of the present invention implemented asan add-on accessory to existing surgical stapler instrument include areduced cost of use and ease of use to a physician who is alreadyfamiliar with the operation of such surgical stapler instrument. In analternate embodiment a surgical device of the present invention may beintegrated with or configured as an add-on accessory to a surgicalinstrument dedicated to implementation of the capabilities offered by asurgical device of the present invention, which may generally comprisetwo opposing jaw members comprising a tool assembly, corresponding to anend effector of a surgical stapler instrument, fixedly and operablyattached to a handle assembly via an elongate body and configured toopen and close when operated by the handle assembly. Although theimplementation and operation of a surgical device in various embodimentsof the present invention will be described in the following as itrelates to a endoscopic surgical stapler instrument and endoscopicsurgical instrument, it should be apparent to those of skill in the artthat the aspects of the present disclosure may be readily adapted foruse with other surgical stapler instruments as well as other types ofsurgical instruments.

The present invention is being discussed in terms of endoscopicprocedures and apparatus. However, use herein of terms such as“endoscopic”, should not be construed to limit the present invention toa surgical instrument for use only in conjunction with an endoscopictube (i.e., trocar). On the contrary, it is to be understood that thepresent invention may find use in any procedure where access is limitedto a small incision, including but not limited to laparoscopicprocedures, as well as open procedures.

The characteristic behavior of a tissue undergoing deformation underexternal stress load, for example, a compressive stress load applied bya pair of jaw members comprising an end effector of a surgical staplerinstrument, has been widely studied (for example, Jacob Rosen et. al.,“Biomechanical Properties of Abdominal Organs In Vivo and PostmortemUnder Compression Loads,” Journal of Biomedical Engineering, Vol. 130,pp. 1-17) and is generally represented by a stress-strain curve plot,well known to those of skill in the art, shown in FIG. 1 in an exemplaryrepresentation for a stomach tissue. In response to a compressive stressload, depicted in the vertical axis of the plot, the stomach tissueundergoes a rapid deformation, represented as strain, defined as apercentile reduction in tissue thickness, and depicted in the horizontalaxis of the plot, in response to a relatively small change in thecompressive stress load at the lower level thereof. At the higher levelthe stress-strain curve becomes close to a line indicating a linearelastic behavior of the stomach tissue characterized by an elasticmodulus defined as the largely constant slope of the stress-straincurve. This general characteristic behavior of a stomach tissue as wellas other bodily tissue under a compressive stress load is oftendescribed as a viscoelastic behavior, by those of skill in the art,exhibiting typical characteristics of both a viscous liquid and anelastic solid subject to an external compressive stress load. Theinitial rapid deformation of the stomach tissue at the lower level ofcompressive stress load is largely due to initial displacement ofviscous, liquid-like components of the tissue causing a rapid reductionin thickness of the tissue under a relatively weak compressive stressload applied to an area thereof. The elastic response of the tissue atthe higher level of compressive stress load is largely due to relativelyimmobile fibrous, solid-like components of the tissue responding to thecompressive stress load collectively with substantially elasticbehavior. At further higher up in the compressive stress load level thestrain of the tissue reaches what is known to those of skill in the artas the ultimate tensile strength or the breaking point, labeled with aletter C in FIG. 1 where the internal structure of the tissue starts tobreak down and eventually completely loses ability to recoverablyrespond to an additional compressive stress load.

The almost linear correlation between the stress and strain of a stomachtissue and, to an extent, similar behavior exhibited in other bodilytissues at the compressive stress load interval of interest,particularly, as it relates to a surgical stapling operation, indicatedby a bracket labeled with a letter S in FIG. 1, makes it possible toinfer the change in the compressive stress load acting on the stomachtissue if the change in the thickness of the stomach tissue resultingtherefrom is known and vice versa. Based on this observation, one coulddevise a practical scheme for the selection of a staple cartridge,containing staples of optimal height for a tissue of a surgical staplingoperation, from the standard set of staple cartridges, which generallyinclude steps of compressing a tissue to a predetermined thickness,i.e., to a predetermined strain; measuring a compressive stress load,i.e., a reactionary load from the compressed tissue, required to causesuch reduction in thickness; comparing the measured compressive stressload to the known optimal value for a surgical stapling operation, forexample, 8 g/mm² as previously described in the BACKGROUND, noting thesize of difference between the measured compressive stress load and theoptimal value; and based on the result of comparison, deciding whetherto select a staple cartridge with staples of formed height closest tothe compressed tissue thickness or of different formed heights takinginto account the size of difference, i.e., change the strain induced onthe tissue to a direction and level to modify the compressive stressload exerted on the tissue to be closer to the optimal value. As will bedescribed in detail hereinafter, implementation of such a scheme on aplatform of existing surgical instrument, particularly, a surgicalstapler instrument may heavily rely on being able to methodicallyconstrain the closure of the two jaw members comprising an end effectoror a tool assembly to compress a tissue consistently to a predeterminedthickness with a high degree of repeatability and to measure areactionary load from the compressed tissue.

Referring to FIGS. 2A and 2B, an exemplary surgical stapler instrument10 and an enlarged view of an end effector 20 thereof are shown.Surgical stapling instrument 10 includes a handle assembly 11, endeffector 20 and an elongate tube 12 that operatively connects handleassembly 11 and end effector 20 through a drive mechanism (not shown inthe FIGURES). End effector 20 comprises a first jaw member 21 and asecond jaw member 22. Second jaw member 22 comprises an elongate channel23, sometimes referred to as a cartridge bay, configured to receive astaple cartridge 25 having a tissue contacting surface 26. First jawmember 21 comprises an anvil having a tissue contacting surface 24 thatis aligned and pivotally engaged through a pivot mechanism (not shown)with second jaw member 22 forming a pair of opposed jaw members thatopen and close, when driven by the drive mechanism operated with handleassembly 11 by a physician, to capture and compress a tissuethere-between for stapling. Various different drive mechanisms, wellknown to those of skill in the art, are employed to actuate a pivotmechanism joining two jaw members 21, 22 to cause opening and closingthereof including a drive pin and cam groove mechanism, reciprocatingclosure tube assemblies, gear mechanisms, rack and pinion mechanism, andpulley mechanism, etc. Typically, handle assembly 11 driving endeffector 20 is configured in such a way that first and second jawmembers 21, 22 are capable of rigidly holding their approximatedpositional relationship, i.e., a locked position, when closed to captureand compress the tissue prior to the deployment and formation ofstaples. Those of skill in the art would appreciate that the exemplarysurgical stapler instrument depicted in the FIGURES comprises onesurgical stapler instrument version with which various embodiments of asurgical device of the present invention may be advantageously employed.

The pivotal engagement between two jaw members 21, 22 comprising an endeffector 20 may take various configurations including a hinge aboutwhich two jaw members 21, 22 are configured to rotate and a cam groovealong which a drive pin is configured to translate to open or close endeffector 20. The clearances built in the mechanical designs of the pivotmechanism and the drive mechanism to ensure smooth operations thereofand, to a lesser extent, unavoidable manufacturing tolerances in theparts thereof inevitably introduce a measurable play in the pivotalmotion of two jaw members 21, 22, which manifests as an inherentuncertainty in the positional relationship between two jaw members 21,22, particularly, in the relative angular position thereof even underunloaded condition, that is, without a tissue captured and compressedthere-between. Of particular significance to a device and method in anembodiment of the present invention is a variation in the relativeangular position of the two jaw members that may be appropriatelyreferred as a backlash, i.e., a tendency for the closed jaw members toopen back up, the size of which is strongly dependent on the level ofcompression of a tissue there-between. The variation in the backlashintroduces, in effect, variability in the gap distance, defined as adistance between tissue contacting surfaces 24, 26, of two jaw members21, 22 at a given position along the length of end effector 20, whichalso varies with the size of a reactionary load from the compressedtissue. The uncertainty in the gap distance due to the play in the pivotmechanism tends to become more pronounced going farther away distallyfrom pivot mechanism due to a lever arm effect. A reactionary load fromthe compressed tissue acting on two jaw members 21, 22 may add tovariability in the gap distance by potentially causing a deformation ora deflection of two jaw members 21, 22, more likely, an anvil the lessstiffer of the two, the degree of which differs depending the size ofthe reactionary load and, therefore, is not easy to estimate or measure.In practice, the gap distance has been observed to vary verysignificantly from one tissue to another mostly due to the deflection ofthe anvil, irrespective of particular brands of surgical staplerinstrument in the market, and in fact, there are no dedicated mechanismsimplemented on the existing surgical stapler instrument products toprecisely and actively control the gap distance during compression of atissue. Instead, when critically needed, for example, in case of a verythick tissue, an external constraining means is employed to control thegap distance to some extent in certain surgical stapler instruments inthe market. For this reason, a surgical stapler instrument presentlybeing marketed does not make a suitable platform on which to implementthe staple cartridge selection scheme, described previously, whichhinges on an ability to compress a tissue consistently to a well definedthickness and measure a reactionary load therefrom. A surgical deviceand method proposed in this disclosure seeks to remedy such deficienciesin a surgical stapler instrument or a new surgical instrument dedicatedfor implementation of such a scheme with a mechanical and operationalconfiguration similar to those of a surgical stapler instrument withoutrequiring a radical redesign of the instruments by providing relativelysimple features that are added-on to help bring under control thevariability in the gap distance between the two jaw members comprisingan end effector or a tool assembly and to introduce a capability to theinstruments to measure a reactionary load from the compressed tissue aswill be described hereinafter.

Referring to FIG. 3A, a compression gauge cartridge 30 is shown, in aperspective view, mounted in cartridge bay 23 of cartridge jaw member 22of end effector 20 of surgical stapler instrument 10, as shown in FIGS.2A and 2B, for compressing a tissue consistently to a predeterminedthickness and measuring a reactionary load therefrom in an embodiment ofthe present invention. Anvil jaw member 21 is omitted for clarity inFIG. 3A and a pivot mechanism joining the two jaw members 21, 22 isschematically represented by a symbol labeled with a letter P and apivotal motion by a double headed, curved arrow labeled with a letter A.In FIG. 3B compression gauge cartridge 30 is shown released fromcartridge bay 23. Referring to FIG. 3C, details of construction ofcompression gauge cartridge 30 is shown in an exploded view in anembodiment of the present invention. In a preferred embodiment of thepresent invention, compression gauge cartridge 30 for use mounted incartridge bay 23 of cartridge jaw member 22 comprising end effector 20of surgical stapler instrument 10, together with anvil jaw member 21having a tissue contacting surface 24, to compress a tissue consistentlyto a predetermined thickness and measure a reactionary load therefromfor assisting in selection of a staple cartridge optimal for a tissue ofa surgical stapling operation and assessing a condition of a tissue of asurgical operation comprises: a cartridge body 31 having a proximal end32 and a distal end 33, and a tissue supporting surface 34 correspondingto tissue contacting surface 26 of staple cartridge 25, whereincartridge body 31 may be configured for compression gauge cartridge 30to be releasably mounted in cartridge bay 23 and for tissue supportingsurface 34 to be at least at a predetermined distance from tissuecontacting surface 24 of anvil jaw member 21 when cartridge jaw member22 and anvil jaw member 21 are in a fully closed position; a force gaugeassembly 40 comprising a force transducer 41 and a compression head 45having a tissue compression face 46, wherein force gauge assembly 40 maybe supported by cartridge body 31 positioned between proximal end 32 anddistal end 33 thereof, and wherein compression head 45 comprising saidforce gauge assembly 40 may be configured and disposed so that tissuecompression face 46 thereof may lie substantially closer to tissuecontacting surface 24 of anvil jaw member 21 than tissue supportingsurface 34 of cartridge body 31; and a spacer member 50 extending fromtissue supporting surface 34 of said cartridge body 31, wherein forcegauge assembly 40 may be positioned distally with respect to spacermember 50. In an alternate embodiment tissue supporting surface 34 ofcartridge body 31 may be contoured in such a way to further reducecompression of a tissue disposed between tissue supporting surface 34and tissue contacting surface 21 when cartridge jaw member 22 and anviljaw member 21 are in a fully closed position. Further details ofcompression gauge cartridge 30 can be seen in FIG. 3D showing, in aperspective view, cartridge body 31 sectioned along the line 3D-3D shownin FIG. 3C and spaced apart in an embodiment of the present invention.As will become more clear with the following description, compressiongauge cartridge 30 is configured to allow an existing surgical staplerinstrument to be used without modification in applying a compression toa predetermined area of a tissue captured between the two jaw memberscomprising an end effector thereof consistently and with a high degreeof repeatability to a predetermined thickness substantially free ofvariations of mechanical and structural origins and measuring areactionary load from the compressed area of the tissue dynamicallythroughout the compression operation. In an embodiment of the presentinvention cartridge body 31 comprising compression gauge cartridge 30may be configured for compression gauge cartridge 30 to be releasablymounted and securely retained in cartridge bay 23 comprising cartridgejaw member 22 of end effector 20. In an alternate embodiment cartridgebody 31 comprising compression gauge cartridge 30 may be configured tobe fixedly mounted in cartridge bay 23 to be integrated with cartridgejaw member 22 of end effector 20 of surgical stapler instrument 10. Inanother alternate embodiment cartridge body 31 comprising compressiongauge cartridge 30 may be configured to be fixedly mounted in acartridge bay to be integrated with a cartridge jaw member of an endeffector comprising a disposable reload unit of a certain surgicalstapler instrument product in the market.

Referring to FIGS. 3A-3D force transducer 41 comprising force gaugeassembly 40 is depicted as having a configuration of a beam supported bycartridge body 31 housed in a cavity 35 therein in an embodiment of thepresent invention. In an alternate embodiment force transducer 41comprising force gauge assembly 40 may have a configuration of a buttonsupported by cartridge body 31 housed in a cavity 35 therein as shown inFIGS. 4A and 4B in similar arrangements to FIGS. 3A and 3D,respectively. In another alternate embodiment force transducer 41comprising force gauge assembly 40 may have a substantially planarconfiguration supported by cartridge body 31 disposed on tissuesupporting surface 34 thereof as shown in FIGS. 5A and 5B in similararrangements to FIGS. 3A and 3D, respectively. In various embodiments ofthe present invention cartridge body 31 comprising compression gaugecartridge 30 provides a structurally stable platform upon which forcetransducer 41 relies in performing a force measurement operation exertedthereon. More detailed descriptions will follow hereinafter in a sectiondedicated to the force transducer.

In an embodiment of the present invention cartridge body 31 comprisingcompression gauge cartridge 30 may be configured to include selecteddesign features similar to those found in a conventional staplecartridge that allow a conventional staple cartridge to be releasablymounted and securely retained in a cartridge bay of a cartridge jawmember during a stapling operation. In an alternate embodiment cartridgebody 31 may include additional design features for releasable mountingand secure retention thereof in a cartridge bay and safety features forsafe and effective use of a surgical stapler instrument instrumentedwith compression gauge cartridge 30 by a physician with average level ofexperience and skill in use of an ordinary surgical stapler instrument.In an embodiment, materials and method of manufacture substantiallysimilar to those used to construct a conventional staple cartridge maybe employed and appropriately adapted to manufacture cartridge body 31comprising compression gauge cartridge 30. In an alternate embodimentcartridge body 31 may include structural reinforcements and/orunconventional construction materials, not ordinarily found in aconventional staple cartridge, to ensure proper operation of force gaugeassembly 40 comprising compression gauge cartridge 30 and compression ofa tissue in cooperation with an anvil jaw member comprising an endeffector. As will be described hereinafter, the distribution of areactionary load on cartridge body 31 from a tissue under compression inoperation of surgical stapler instrument 10 instrumented withcompression gauge cartridge 30 may be different, by design, from that ona conventional staple cartridge mounted in a cartridge bay of the sameor comparable surgical stapler instrument in an embodiment of thepresent invention.

Referring to back FIGS. 3C and 3D, in an embodiment of the presentinvention cartridge body 31 may be configured to support force gaugeassembly 40 in an open cavity 35 defined therein with an opening 36disposed on tissue supporting surface 34 interconnecting cavity 35 andan external space above tissue supporting surface 34, through whichcompression head 45 comprising force gauge assembly 40 is disposed. Inan embodiment opening 36 may be hermetically capped with a seal member37 to prevent introduction of unwanted contaminant, such as bodilyfluid, into cavity 35. Seal member 37 may be configured to be in contactwith tissue compression face 46 of compression head 45 and provided withsufficient flexibility or, otherwise, a freedom of movement to allowdisplacement of compression head 45 in response to a load exertedthereto from a compressed tissue to take place substantially freely,which is generally very small and required in a normal operation offorce transducer 41, as will be described later in a dedicated section.In an alternate embodiment seal member 37 may be integrated withcompression head 45 on tissue compression face 46 thereof tosubstantially freely move concurrently therewith. In an embodimentcavity 35 may be configured, preferably, to substantially rigidly hold astationary portion of force transducer 41 of a beam configuration toprovide a structural support necessary for optimal operation thereof andto leave sufficient space to ensure unobstructed deflection of adeflectable portion of force transducer 41 and compression head engagedtherewith, which is a key aspect of force measurement operation of aforce transducer of a beam configuration, as is well known to those ofskill in the art. Referring to FIG. 4B, in an embodiment of the presentinvention cavity 35 may be configured to accommodate to rigidly holdforce transducer 41 of a button configuration and leave sufficient spacefor free movement of compression head 45 engaged therewith. In a furtherembodiment cartridge body 31 may be configured to support force gaugeassembly 40 of a planar configuration substantially on tissue supportingsurface 34 as shown in FIGS. 5A and 5B. In an embodiment a retentionfeature 49 may be provided to securely position force gauge assembly 40on tissue supporting surface 34.

Referring to FIGS. 6A and 6B, schematically showing a tissue T capturedand compressed, respectively, between anvil jaw member 21 and aconventional staple cartridge 25 representing a cartridge jaw member 22as shown in FIG. 2B, the distributed reactionary load from compressedtissue T over the length of anvil jaw member 21 comprising end effector20 often causes anvil jaw member 21 to deflect to a substantial degreetypically being less stiffer than cartridge jaw member 22 instrumentedwith staple cartridge 25. The extent, to which anvil jaw member 21deflects, strongly depends on the degree of compression of tissue T andgradually increases as one goes distally along the length of endeffector 20 from pivot mechanism P due to a cumulative nature of thereactionary load from compressed tissue T. This is a major reason why itis not practically possible to controllably compress a tissueconsistently to a known thickness with existing surgical staplerinstrument mounted with a conventional stapler cartridge in a cartridgejaw member thereof in addition the inevitable plays in the pivot anddrive mechanisms.

With a view to substantially eliminate incontrollable deflection of ananvil jaw member, comprising an end effector together with a cartridgejaw member instrumented with a compression gauge cartridge, inperforming tissue compression captured there-between, in an embodimentof the present invention, cartridge body 31, as shown in FIG. 6C in aperspective view, may be configured so that tissue supporting surface 34thereof may be at the minimum at a predetermined distance from a tissuecontacting surface of an anvil jaw member when a cartridge jaw memberand an anvil jaw member are in a fully closed position with or without atissue captured and compressed there-between. Preferably, the gapdistance, defined as a distance between tissue supporting face 34 andthe tissue contacting surface of an anvil jaw member, at a positionalong the length of the end effector may be substantially larger thanthe largest gap distance provided by any one from the standard set ofstaple cartridges at the same position and under the same loadingcondition from the compressed tissue, if present, so that compression ofa tissue disposed over an area covered by tissue supporting surface 34may be minimized to substantially eliminate a distributed reactionaryload acting on the anvil jaw member. In an embodiment tissue supportingsurface 34 may include surface contours such as a recess 38 in order tofurther reduce compression applied to a tissue in contact therewith. Theneed to keep the tissue compression under control over the area oftissue supporting surface 34 must be balanced against the requirementfor the structural stiffness of a cartridge jaw member to guard againstdeformation thereof. Referring back to FIG. 3B, in an embodiment of thepresent invention cartridge body 31 may be configured for tissuesupporting surface 34 thereof to lie substantially even with a topportion 28 of cartridge bay 23. In an alternate embodiment, cartridgebody 31 may be configured for tissue supporting surface 34 thereof tolie substantially above top portion 28. In another alternate embodiment,cartridge body 31 may be configured for tissue supporting surface 34thereof to lie substantially below top portion 28.

Located at a predetermined position along the length of cartridge body31 on tissue supporting surface 34 thereof is an opening 36, as shown inFIGS. 3C, 3D and 4B, in an embodiment of the present invention, throughwhich compression head 45 comprising force gauge assembly 40 isdisposed. In an alternate embodiment, as shown in FIGS. 5A and 5B, forcegauge assembly 40 comprising force transducer 41 of a planarconfiguration and compression head 45 may be disposed at a predeterminedposition along the length of cartridge body 31 on tissue supportingsurface 34. In a preferred embodiment of the present inventioncompression head 45 comprising force gauge assembly 40 may be configuredand disposed with respect to cartridge body 31 so that tissuecompression face 46 thereof lie substantially above tissue supportingsurface 34 of cartridge body 31 and closer to tissue contacting surface24 of anvil jaw member 21, as shown in FIG. 2B, than tissue supportingsurface 34 of cartridge body 31 when cartridge jaw member 22 and anviljaw member 21 are in a fully closed position. Under such configuration,a tissue captured between a compression gauge cartridge mounted in acartridge bay of a cartridge jaw member and an anvil jaw memberexperiences compression substantially exclusively over the area coveredby tissue compression face 46 when two jaw members are in a fully closedposition, as schematically illustrated in FIG. 6D in an embodiment,where a predetermined gap distance over tissue compression face 46 or apredetermined thickness to which a tissue is compressed is labeled by aletter G. In an embodiment of the present invention the area coveredtissue compression face 46 may be varied in order to control areactionary load from a tissue compressed thereon and substantiallyeliminate potential deflection of an anvil jaw member resultingtherefrom. In an alternate embodiment, the position along the length ofthe end effector of compression head 45 comprising force gauge assemblymay be varied to control a lever arm effect, as previously described, ofa reactionary load from a tissue compressed thereon and substantiallyeliminate potential deflection of an anvil jaw member resultingtherefrom as schematically shown in FIG. 6E. In another alternateembodiment, the area of tissue compression face 46 and the positionalong the length of the end effector of compression head 45 may bejointly varied.

Referring to FIGS. 3C-4B and FIGS. 7A and 8A showing, in a perspectiveview, a force gauge assembly 40 comprising force transducer 41 andcompression head 45 where compression head 45 is shown spaced apart fromforce transducer 41, in an embodiment of the present invention, forcegauge assembly 40 may be disposed for compression head 45 to be locatedat a predetermined position along the length of cartridge body 31between proximal end 33 and distal end 32 thereof to provide ameasurement of a reactionary load from a tissue compressed in a gapbetween a tissue contacting surface of an anvil jaw member and tissuecompression face 46 of compression head 45. In a preferred embodimentforce transducer 41 may be a strain gauge based load cell of variousconfigurations capable of generating an electrical signal whenstimulated including load cells of a beam configuration including, forexample, a cantilever bending beam and a parallel bending beam, asschematically illustrated in FIG. 7A, and of a button configuration, asschematically illustrated in FIG. 8A, as are well known to those ofskill in the art. Strain gauge based load cells are widely availablefrom a multitude of vendors at relatively low price levels due to theirwide spread uses in industrial applications and consumer weightmeasurement equipments such as personal and kitchen electronic scales.In an embodiment of the present invention there is provided a signalconduction means 48 electrically connected to force transducer 41 forconducting a signal therefrom to a force transducer indicator or acontroller (not shown in the FIGURES) disposed remotely from thesurgical site, for example, external to a surgery patient. Appropriatesignal conduction means 48 for a strain gauge based load cell and othertypes of load cell generating an electric signal includes a flexibleflat cable and thin gauge electrical wires, both of which are widelyavailable commercially at low cost and of such a small thickness to beable to freely pass through an annular gap between an elongate tube of asurgical stapler instrument and the inside wall of a trocar throughwhich the instrument is deployed. In an alternate embodiment forcetransducer 41 may be a load cell of a planar configuration, asschematically illustrated in FIG. 9A, including a hydraulic load cellcapable of generating a fluid pressure signal when stimulated, apiezoelectric load cell capable of generating an electrical signal whenstimulated, commercially available from a multiple vendors, and aresistive film type force sensor capable of generating an electricalsignal when stimulated, for example, FlexiForce Sensor® commerciallyavailable from Tekscan Inc.

Preferably, signal conduction means 48, appropriately selected for forcetransducer 41, may work bi-directionally conducting a signal from forcetransducer 41 to a force transducer indicator or a controller disposedremotely from a surgical site for signal processing and display ofresult therefrom and providing a power and control signals needed foroperation of force transducer. As shown in FIG. 7C, signal conductionmeans 48 may be routed to pass around a distal end of cartridge jawmember 23 as it exits cartridge body 31 in an embodiment of the presentinvention. As shown in FIG. 7D, in an alternate embodiment, signalconduction means 48 may be configured to comprise at least two parts,one part connected to force transducer 41 on one end and terminatingwith a connector 43 on the other end, and the other part connected to aforce transducer indicator on one end and terminating to a connector 42complementary to connector 43 on the other end. In an embodiment a forcetransducer indicator or a controller may be disposed externally to thepatient and may include an off-the-shelf, commercial weight indicatorunit, a custom designed, microprocessor controlled indicator and asignal processor electronics controlled by a computer with a display. Inan alternate embodiment of the present invention, at least for a forcetransducer configured to be electrically powered and generate anelectric signal when stimulated, an electrical power source, forexample, a battery, and at least a part of processing and displaycircuitry may be disposed in and supported by a cartridge bodycomprising a compression gauge cartridge. In another alternateembodiment the cartridge body may further include a wirelesscommunication means for wirelessly sending a signal to an indicator or acontroller disposed externally from a surgical site for furtherprocessing and display.

In an embodiment, force transducer 41 may be dimensionally adaptable foruse supported in a cartridge body disposed in a cartridge bay of acartridge jaw member of an end effector. In an alternate embodiment,force transducer 41 may be dimensionally adaptable for use supported inone of the jaw members comprising an end effector of a surgicalinstrument dedicated to implementation of the present invention.Preferably, the deflection of a deflectable portion of force transducer41, which normally accompanies operation of force transducer 41 invarying forms and to a different degree, at a maximum level of thereactionary load from the compressed tissue does not exceed apredetermined fraction of a strain induced on the tissue by thecompression applied thereto. As previously described in reference toFIG. 1, a relatively small change in the strain of a tissue, forexample, due to interaction with force transducer 41, could result in asubstantial variation in the stress thereof potentially skewing themeasurement of the reactionary load therefrom. Typically, a maximumdeflection a strain gauge based load cell or a hydraulic load cellexperiences at the load limit does not exceed a few thousandths of aninch easily satisfying the requirement for use on a tissue. A load cellof a planar configuration, at least those include in the examplesdescribed previously, does not require any deflection to perform a forcemeasurement.

In an embodiment of the present invention, compression head 45comprising force gauge assembly 40 mechanically interfaces between atissue undergoing compression and force transducer 41 for measuring areactionary force therefrom. Referring to FIGS. 3A-5B and 7A, 8A and 9A,in an embodiment compression head 45 may be configured and disposed,with respect to cartridge body 31, to contact force transducer 41 on oneend, a transducer contact face 47, and the tissue on the other end,tissue compression face 46 participating in compression of the tissuecooperating with anvil jaw member 21 and transferring a reactionary loadfrom the compressed tissue to force transducer 41 substantially withouta mechanical loss in a manner conducive to the mode of operation of aparticular force transducer. In an embodiment compression head 45 may beconfigured and disposed, with respect to cartridge body 31, so thattissue compression face 46 thereof lies substantially closer to tissuecontacting surface 24 of anvil jaw member 21 than tissue supportingsurface 34 of cartridge body 31 as schematically shown in FIG. 6Dshowing, in a side elevation view, a tissue compressed betweencompression gauge cartridge 30 and anvil jaw member 21 comprising an endeffector in a closed position. This is to deliberately encourage thecompression of a tissue to take place preferentially over an area, outof tissue contacting surface 24 of an anvil jaw member 21, covered bytissue compression face 46 and to minimize tissue compression overtissue supporting surface 34 to a predetermined gap distance betweentissue compression face 46 and tissue contacting surface 24 indicated bya letter G in FIG. 6D.

In various embodiments of the present invention compression head 45 maytake on different configurations and mechanical characteristics thatsuit a particular application of a compression gauge cartridge of thepresent invention. For example, as shown in FIGS. 7B, 8B and 9B,configuration of transducer contact face 47 may be varied to accommodateforce transducer 41 of different geometry, and the area and profile oftissue compression face 46 may be predetermined, for example, to controlthe degree of tissue compression optionally in conjunction withvariation of a gap distance between tissue compression face 46 andtissue contacting surface 24, which is primarily controllable with aspacer member 50, as will be described hereinafter. In an embodimentcompression head 45 may be of substantially rigid construction to beable to transfer a reactionary load imparted on tissue compression face46 thereof to transducer contact face 47 without a mechanical loss evenwhen the reactionary load is unevenly distributed over tissuecompression face 46. In an alternate embodiment compression head 45 maybe of substantially rigid construction to be able to resist deformationunder a compressive load imparted thereon by the compressed tissue butotherwise of flexible nature as may be the case for a relatively thincompression head that may be employed for a force transducer of a planarconfiguration as schematically illustrated in FIG. 9B. In an embodimentof the present invention compression head 45 may be configured to float,that is, be left unattached other than the mechanical engagement withforce transducer 41 through transducer contact face 47 thereof. In analternate embodiment compression head 45 may be fixedly joined withcartridge body 31 in such a configuration that allows a displacementthereof, and concomitant deflection of force transducer 41, in responseto a reactionary load from a compressed tissue to occur through apredetermined deformation of compression head 45. In an exemplaryembodiment, as previously described with reference to FIGS. 3C and 3D,compression head 45 may be fixedly joined with seal member 37 havingsufficient flexibility to provide freedom of movement thereto. In analternate exemplary embodiment, as shown in FIG. 8C, compression head 45may be configured and disposed to cantilever with respect to a fixedposition 49 on cartridge body 31 with tissue compression face 46 thereofpositioned remotely from fixed position 49 and transducer contact face47 positioned there-between. In another alternate exemplary embodiment,compression head 45 may comprise a deformable member 44 fixedly joinedwith cartridge body 31 in a predetermined pattern, for example, alongthe periphery as shown in FIG. 8D schematically illustrating a cartridgebody sectioned and spaced apart, and a force gauge assembly, that isconfigured to flex substantially perpendicularly, i.e., up and down,with respect to tissue contacting surface 46 of cartridge body 31.

Referring to FIGS. 3A-5B, in a preferred embodiment of the presentinvention spacer member 50 may be of a rigid construction extending fromtissue supporting surface 34 of cartridge body 31 disposed betweenproximal end 33 and distal end 32 thereof and proximal to compressionhead 45 comprising force gauge assembly 40. In an embodiment spacermember 50 may be configured to be a positive stop constraining a pivotalmotion of the two jaw members comprising an end effector andsubstantially defining the closest gap distance at the position ofspacer member 50 between tissue contacting surfaces 24, 26 of anvil jawmember 21 and cartridge jaw member 22. In the absence of a deflection ofan anvil jaw member, spacer member 50 also determines a predeterminedgap distance between tissue compression face 46 of compression head 45and tissue contacting surface 24 of anvil jaw member 21 with two jawmembers comprising an end effector in a fully closed position. Spacermember 50 also plays an important role in substantially eliminatingvariation in the gap distance stemming from a play present in the pivotand drive mechanisms of a pivotal joint of the two jaw memberscomprising an end effector. Referring to FIGS. 10A and 10B schematicallyshowing, in a side elevation view, a positional relationship between acartridge jaw member represented by compression gauge cartridge 30 andan anvil jaw member in a fully closed position, in an embodiment of thepresent invention, spacer member 50 may be dimensioned to make the twoplanes, substantially defined by tissue supporting surface 34 and tissuecontacting surface 24, respectively, to be substantially parallel witheach other in providing a predetermined gap distance G between tissuecompression face 46 and tissue contacting surface 24. In an alternateembodiment spacer member 50 may be dimensioned to make the two planes tobe at a predetermined angle with each other in providing a predeterminedgap distance G between tissue compression face 46 and tissue contactingsurface 24. In a further embodiment spacer member 50 may be dimensionedso that substantially all the plays in a pivot mechanism and a drivemechanism of a pivotal joint of the two jaw members are fully taken upwhen the two jaw members are in fully closed position as will be furtherdescribed in the following section.

In a preferred embodiment of the present invention, spacer member 50comprising compression gauge cartridge 30 may be a block of a rigidconstruction fixedly joined with cartridge body 31. As shown in FIG.11A, in an embodiment cartridge body 31 and spacer member 51 may beconfigured so that the position of spacer member 51 along the length ofcartridge body 31 may be changed to suit a particular application of acompression gauge cartridge of the present invention. Spacer member 50plays a significant role in substantially eliminating variation in thepositional relationship between the two jaw members comprising an endeffector due to plays present in the pivot and drive mechanisms of apivotal joint of the two jaw members by acting as a rigid fulcrumdisposed between the pivot mechanism and a compression head comprising aforce gauge assembly that forces the plays to be fully taken up when thetwo jaw members reach a fully closed and, in some cases, lockedposition. Even when the tissue contacting surface of the anvil jawmember comes to rest making contact with the spacer member as the twojaw members close driven by the drive mechanism, the drive mechanismcontinues to drive the pivot mechanism to rotate one or both of the jawmembers with respect to the point of contact between the anvil jawmember and the spacer member until all the plays in the pivot and drivemechanisms are fully taken up and the pivotal motion of the two jawmembers comes to a solid stop reaching a final positional relationshipthere-between. Since, in practice, the force involved in driving thepivotal motion of the two jaw members are, by design, much larger thanthe largest reactionary load normally expected from a compressed tissuebetween the two jaw members comprising an end effector of a surgicalstapler instrument, the final positional relationship between the twojaw members thus achieved remains substantially undisturbed even whenthe two jaw members are acted upon from the reactionary load from acompressed tissue there-between and is solely determined by the positionand configuration of spacer member 50. Barring potential deflection ofthe anvil jaw member under a reactionary load from a compressed tissue,which can be effectively kept under control as previously described,spacer member 50 thus enables a surgical stapler instrument implementedwith a compression gauge cartridge of the present invention to be used,without modification, to provide a predetermined gap distance, betweenthe compression face of the compression head and the tissue contactingsurface of the anvil jaw member, consistently and with high degree ofrepeatability, and concomitantly to compress a tissue consistently to athickness corresponding to the predetermined gap distance.

In an embodiment of the present invention, a spacer member alsofunctions as a tissue stop defining a proximal most position along thecartridge body to which a tissue can be introduced between the two jawmembers comprising an end effector. Referring to FIGS. 11B and 11C, inan embodiment spacer member 55, 60 may further comprise a spacerextension member 57, 62 for preventing a portion of a tissue gettingcaught, while being captured, and subsequently pinched between a spacermember and a tissue contacting surface of an anvil jaw member as the twojaw members are closed. As shown in FIG. 11B, in an embodiment spacerextension member 57 may be of a retractable/extendable type configuredto move in and out of a spacer member body 56, for example, a spring 58loaded plunger or detent biased to extend out of a cavity in spacermember body 56 to a preset limit and to follow the pivotal motion of thetwo jaw members keeping the gap between the spacer member and the tissuecontacting surface of an anvil jaw member closed. In an alternateembodiment, as shown in FIG. 11C, spacer extension member 62 may be of acollapsible/expandable type including an air filled bladder, resilientfoam, a metal spring element and a leaf spring element made of a stiffpolymer film, etc, configured to require a minimal force to be collapseddown to a spacer member body 61. Referring to FIG. 11D, in an embodimenta compression gauge cartridge may comprise a protective cover 39providing protection, for example, undesirable impact during handling,over at least part of cartridge body 31 thereof, preferably, includingthe general area around the position of the force gauge assembly.

Referring to FIGS. 12A-12C showing a spacer member, and a cartridge body31 and a cartridge bay 23 broken away and sectioned apart, in anembodiment of the present invention, a spacer member comprising acompression gauge cartridge may be configured so that the height thereofover the tissue supporting surface of the cartridge body, i.e., thevertical extent the spacer member extends from the tissue supportingsurface, may be adjusted. As shown in FIG. 12A, in an embodiment of thepresent invention, an adjustable spacer member 65 having an anvilcontacting face 66 may be mounted on a threaded base 67 of a genderdisposed in a hole 69 in cartridge body 31 with a matching thread of anopposite gender so that the vertical position of anvil contacting face66 may be adjusted by turning a control stem 68 fixedly joined withthreaded base 67 and disposed through a slot normally found in cartridgebay 23. As shown in FIG. 12B, in an alternate embodiment, an adjustablespacer member 70 having an anvil contacting face 71 may comprise a rigidbase 72 disposed in a hole 75 in cartridge body 31 and on a wedge shapeplatform 73 joined with a control stem 74 disposed through a slot incartridge bay 23 so that the vertical position of anvil contacting face71 may be adjusted and locked in a position by sliding control stem 74along the slot. As shown in FIG. 12C, in another alternate embodiment,an adjustable spacer member 76 may be configured to have a nestedstructure comprising a stationary base 77 and a movable plunger 78slidably engaged with stationary base 77 in a hole 8 lfor verticalmovement with respect to the tissue supporting surface and to include atleast one break member 79 with a predetermined breaking mechanism, forexample, a sharp edge, drivable with control stems 80 fixedly joinedtherewith and disposed through a slot in cartridge bay 23 so thatmovable plunger 78 may be securely held immobile once the desiredvertical position thereof is reached. In an embodiment adjustable spacermember 65, 70, 76 may be configured with a bias spring that drivesadjustable spacer member or a movable part thereof to a final positionwhen triggered by a predetermined event, an example of which will bedescribed hereinafter.

As shown in FIGS. 12D and 12E, in an embodiment of the present inventiona spacer member 100 may be configured to include an axle 104, a springelement 103 and at least one flap member 101, and to be disposed in acavity 102 in a cartridge body comprising a compression gauge cartridgewith axel 104 rotatably mated with a pair of holes 105 in the cartridgebody so that spacer member 100 may pivot with respect to the cartridgebody around axle 104. Spring element 103 may be configured to biasspacer member 100 so that it remains up right with respect to thecartridge body ready to withstand the downward load from the anvilmember when the two jaw members comprising the end effector are in afully closed position. At least one flap member 101 may be configuredand disposed with respect to spacer member 100 so that it may be flippedproximally and distally therewith when acted on by the proximal anddistal ends of a trocar, respectively, during insertion and removalthere-through of a surgical stapler instrument instrumented with thecompression gauge cartridge. In an embodiment spacer member 100 may berotated to reduce the height thereof above the cartridge body, asschematically shown in FIG. 12E, manually by a physician prior toinsertion of a surgical stapler instrument or automatically by theinteraction thereof with the distal end of the trocar during removal ofa surgical stapler instrument. A spacer member of such a configurationwould enable use of a compression gauge cartridge with a spacer memberso tall that would make an end effector of a surgical stapler instrumentinstrumented with a compression gauge cartridge impassable through anormally used trocar even with the jaw members in a fully closedposition.

Surgical stapler instrument products of a design, like any otherengineering products, inherently includes certain variations in theirmechanical performance, which, by design, are not of significance inoriginally intended uses in surgical stapling operation but maynegatively affect uses of a surgical stapler instrument instrumentedwith a compression gauge cartridge of the present invention. Forexample, such variations could manifest between different productionlots, for example, due to change in production steps and/or even betweendifferent instruments from the same production lot, for example, due tochanges in the manufacturing tolerances of parts and/or subassemblies.As described previously, changes in the plays in the pivot and drivemechanism of a surgical stapler instrument, for example, resulting fromvariations in manufacturing tolerances may degrade the precision in thefinal positional relationship between the two jaw members in a fullyclosed and locked position and, in turn, the predetermined gap distancebetween the tissue compression face of the compression head and thetissue contacting surface of the anvil jaw member corresponding to apredetermined thickness to which a tissue is compressed. To circumventthe potential impact these variations may have on the performance of acompression gauge cartridge mounted on a surgical stapler instrument orin a surgical compression gauge instrument, in various embodiments ofthe present invention, there are provided methods for calibrating thegap distance between the tissue compression face of the compression headand the tissue contacting surface of the anvil jaw member. Referring toFIG. 13A showing, in a side elevation view, an anvil jaw member 21 and acompression gauge cartridge 30 representing a cartridge jaw member, inan embodiment a gap distance calibration method comprises steps of: (1)positioning a reference block 85 over a compression head 45 of heightcorresponding to a predetermined gap distance between tissue compressionface 46 of compression head 45 and the tissue contacting surface 24 ofanvil jaw member 21; (2) fully closing the two jaw members of the endeffector; and (3) adjusting the height of an adjustable spacer member 90until the load cell indicator reads zero. In an embodiment the height ofreference block 85 may be fine tuned to reflect possible deflection ofanvil jaw member 21 due to a reactionary load from reference block 85during the gap distance calibration procedure. For example, referenceblock 85 may be made taller than a predetermined target gap distance toaccount for deflection of anvil jaw member 21. In an embodiment fullyclosing the two jaw members may involve operating a handle assemblycomprising a surgical stapler instrument or a surgical compression gaugeinstrument to close the two jaw members until the handle assemblyreaches a locked state corresponding to a limit of the closingoperation. In an alternate embodiment a gap distance calibration methodcomprises steps of: (1) positioning reference block 85 over acompression head 45 of height corresponding to a predetermined gapdistance between tissue compression face 46 of compression head 45 andtissue contacting surface 24 of anvil jaw member 21; (2) fully closingthe two jaw members of the end effector; and (3) adjusting the height ofadjustable spacer member 90 until it touches tissue contacting surface24 of anvil jaw member 21. In another alternate embodiment a gapdistance calibration method comprises steps of: (1) positioning areference material over a compression head 45 of known tensile propertyand dimension between tissue compression face 46 of compression head 45and tissue contacting surface 24 of anvil jaw member 21; (2) fullyclosing the two jaw members of the end effector; and (3) adjusting theheight of adjustable spacer member 90 until the load cell indicatorreads a predetermined value indicating the reference material iscompressed to a thickness corresponding to a predetermined gap distancebetween tissue compression face 46 of compression head 45 and tissuecontacting surface 24 of anvil jaw member 21. As shown in FIGS. 13B and13C, in an embodiment of the present invention a protective cover 87 maybe configured to comprise a built-in reference block 88 and a triggermember 91 for causing a spring 92 to drive a locking mechanism 73, 74for adjustable spacer member 70 to facilitate the gap calibrationprocedure.

Referring to FIG. 14, in an embodiment of the present invention, acompression gauge cartridge 30 may comprise two parts 96, 97,preferably, one part 96 including a force gauge assembly 40 and theother part 97 including a spacer member 95, that are configured to bereleasably joined with each other. In an embodiment part 96 may be apart of compression gauge cartridge 30 that can be effectivelyre-sterilized and part 97 difficult to re-sterilize, for example, due tointernal structures present if spacer member 95 is an adjustable spacermember as previously described. After use, part 96 may be kept for reusefollowing a re-sterilization and used part 97 may be discarded andexchanged with a new one.

Referring to FIG. 15, in an embodiment of the present invention, asurgical compression gauge instrument 110 for compressing a tissueconsistently to a predetermined thickness and measure a reactionary loadtherefrom for assisting selection of a staple cartridge and assessing acondition of a tissue comprises: a handle portion 111; a body portion112 extending distally from handle portion 111 and defining alongitudinal axis; and a tool assembly 120 at a distal end of andoperatively connected to body portion 112, tool assembly 120 comprisingan anvil jaw member 121 having a tissue contacting surface 122 and acompression gauge jaw member 125, configured to open and close whenoperated by handle portion 111, wherein compression gauge jaw member 125having a proximal end 126 and a distal end 127, and a tissue supportingsurface 128 comprises a force gauge assembly 129 comprising a forcetransducer (not shown in the FIGURE) and a compression head 130 having atissue compression face 131, supported by compression gauge jaw member125 positioned between proximal end 126 and distal end 127 thereof, andwherein compression head 130 of force gauge assembly 129 is disposed sothat tissue compression face 131 thereof lies substantially closer totissue contacting surface 122 of anvil jaw member 121 than tissuesupporting surface 128 of compression gauge jaw member 125; and a spacermember 132 extending from tissue supporting surface 128 comprisingcompression gauge jaw member 125, wherein force gauge assembly 129 ispositioned distally with respect to spacer member 132.

In a preferred embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a predeterminedcartridge from the set of standard staple cartridges, between a tissuecompression face of a compression head comprising a force gauge assemblycomprising said compression gauge cartridge and a tissue contactingsurface of said anvil jaw member; capturing a tissue between saidcartridge jaw member and said anvil jaw member; closing said cartridgejaw member and said anvil jaw member to compress said tissue capturedbetween said tissue compression face and said tissue contacting surfaceto a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; comparing saidreactionary load reading with a value known to be optimal for a staplingoperation of said tissue to determine if said reactionary load is case(1) within, case (2) below or case (3) above a window of a predeterminedwidth around said optimal value and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height corresponding to saidpredetermined thickness of said compressed tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (2), or a staple cartridge containing staples of aheight larger than said predetermined thickness of said compressedtissue taking into account said size of difference if the result ofcomparison is case (3). In an alternate embodiment, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation may further comprise a step of waitingfor a predetermined length of time after closing said cartridge jawmember and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined average height, optimal for atissue of a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to an average height of staples contained in apredetermined cartridge from the set of standard staple cartridges,between a tissue compression face of a compression head comprising aforce gauge assembly comprising said compression gauge cartridge and atissue contacting surface of said anvil jaw member; capturing a tissuebetween said cartridge jaw member and said anvil jaw member; capturing atissue between said cartridge jaw member and said anvil jaw member;closing said cartridge jaw member and said anvil jaw member to compresssaid tissue captured between said tissue compression face and saidtissue contacting surface to a predetermined thickness corresponding tosaid gap distance there-between; reading out a reactionary load fromsaid compressed tissue displayed on a force transducer indicator;comparing said reactionary load reading with a value known to be optimalfor a stapling operation of said tissue to determine if said reactionaryload is case (1) within, case (2) below or case (3) above a window of apredetermined width around said optimal value and how large a size ofdifference is in cases (2) and (3); selecting a staple cartridge fromsaid standard set of staple cartridges containing staples of an averageheight corresponding to said predetermined thickness of said compressedtissue if the result of comparison is case (1), or a staple cartridgecontaining staples of an average height smaller than said predeterminedthickness of said compressed tissue taking into account said size ofdifference if the result of comparison is case (2), or a staplecartridge containing staples of an average height larger than saidpredetermined thickness of said compressed tissue taking into accountsaid size of difference if the result of comparison is case (3). In analternate embodiment, a method for selecting a staple cartridge from thestandard set of staple cartridges, each containing staples of apredetermined average height, optimal for a tissue of a surgicalstapling operation may further comprise a step of waiting for apredetermined length of time after closing said cartridge jaw member andsaid anvil jaw member to compress said tissue.

In another alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance,corresponding to a height of staples contained in a green cartridge fromthe set of standard staple cartridges, between a tissue compression faceof a compression head comprising a force gauge assembly comprising saidcompression gauge cartridge and a tissue contacting surface of saidanvil jaw member; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured between said tissuecompression face and said tissue contacting surface to a predeterminedthickness corresponding to said gap distance there-between; reading outa reactionary load from said compressed tissue displayed on a forcetransducer indicator; comparing said reactionary load reading with avalue known to be optimal for a stapling operation of said tissue todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said optimalvalue; selecting a green cartridge from the standard set of staplecartridges if the result of comparison is case (1) or a blue cartridgeif the result of comparison is case (2), or a black cartridge if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member, of a surgical stapler instrument, a spacer member ofwhich is configured to consistently provide a gap distance between atissue compression face of a compression head comprising a force gaugeassembly comprising said compression gauge cartridge and a tissuecontacting surface of said anvil jaw member; capturing a tissue betweensaid cartridge jaw member and said anvil jaw member; closing saidcartridge jaw member and said anvil jaw member to compress said tissuecaptured between said tissue compression face and said tissue contactingsurface to a predetermined thickness corresponding to said gap distancethere-between; reading out a reactionary load from said compressedtissue displayed on a force transducer indicator; providing a referencetissue for which an optimal staple height for a surgical staplingoperation is known; comparing said reactionary load reading with areactionary load from said reference tissue compressed to saidpredetermined thickness over the same area of said reference tissue asthat of said tissue compression face of said compression head todetermine if said reactionary load is case (1) within, case (2) below orcase (3) above a window of a predetermined width around said reactionaryload from said reference tissue and how large a size of difference is incases (2) and (3); selecting a staple cartridge from the standard set ofstaple cartridges containing staples of a height known to be optimal forsaid reference tissue if the result of comparison is case (1), or astaple cartridge containing staples of a height smaller than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (2),or a staple cartridge containing staples of a height larger than that ofstaples known to be optimal for said reference tissue taking intoaccount said size of difference if the result of comparison is case (3).In an alternate embodiment, a method for selecting a staple cartridgefrom the standard set of staple cartridges, each containing staples of apredetermined height, optimal for a tissue of a surgical staplingoperation may further comprise a step of waiting for a predeterminedlength of time after closing said cartridge jaw member and said anviljaw member to compress said tissue.

Referring to FIG. 16, showing a compression gauge cartridge 30 in aperspective view in an embodiment of the present invention, compressiongauge cartridge 30 for use mounted in a cartridge bay of a cartridge jawmember comprising an end effector of a surgical stapler instrument,together with an anvil jaw member having a tissue contacting surface, tocompress a tissue so that said cartridge jaw member and said anvil jawmember come to a predetermined angular positional relationship with eachother, as indicated in FIG. 17 by a label AG in a schematicrepresentation of an anvil jaw member 21 and compression gauge cartridge30, and measure a reactionary load therefrom for assisting in selectionof a staple cartridge optimal for a tissue of a surgical staplingoperation comprises: a cartridge body 31 having a proximal end 32 and adistal end 33, and a tissue supporting surface 34, wherein cartridgebody 31 may be configured for compression gauge cartridge 30 to bereleasably mounted in said cartridge bay and for tissue supportingsurface 34 to be at least at a predetermined distance from said tissuecontacting surface of said anvil jaw member when cartridge jaw memberand said anvil jaw member are in a fully closed position; and a forcegauge assembly 40 comprising a force transducer and a compression headhaving a tissue compression face, wherein force gauge assembly 40 may besupported by cartridge body 31 positioned between proximal end 32 anddistal end 33 thereof, and wherein said compression head comprising saidforce gauge assembly 40 may be configured and disposed so that saidtissue compression face thereof may lie substantially closer to saidtissue contacting surface of said anvil jaw member than tissuesupporting surface 34 of cartridge body 31. In an alternate embodimenttissue supporting surface 34 of cartridge body 31 may be contoured insuch a way to further reduce compression of a tissue disposed betweentissue supporting surface 34 and said tissue contacting surface whensaid cartridge jaw member and said anvil jaw member are in a fullyclosed position. Compression gauge cartridge 30 is configured to allowan existing surgical stapler instrument to be used without modificationin applying a compression to a predetermined area of a tissue capturedbetween the two jaw members comprising an end effector thereof so thatthe two jaw members come to a predetermined positional relationship witheach other and measuring a reactionary load from the compressed area ofthe tissue. In an embodiment of the present invention cartridge body 31comprising compression gauge cartridge 30 may be configured forcompression gauge cartridge 30 to be releasably mounted and securelyretained in a cartridge bay comprising a cartridge jaw member of an endeffector. In an alternate embodiment cartridge body 31 comprisingcompression gauge cartridge 30 may be configured to be fixedly mountedin a cartridge bay to be integrated with a cartridge jaw member of anend effector of a surgical stapler instrument. In another alternateembodiment cartridge body 31 comprising compression gauge cartridge 30may be configured to be fixedly mounted in a cartridge bay to beintegrated with a cartridge jaw member of an end effector comprising adisposable reload unit of a certain surgical stapler instrument productin the market. In an alternate embodiment of the present invention thedimension of a cartridge body comprising a compression gauge cartridgemay be varied to suit particular application thereof. For example, asshown in FIG. 19, cartridge body 31 may be configured to be shorter thana conventional staple cartridge along the length of a cartridge bay.

Referring to FIG. 18, in an embodiment of the present invention, asurgical stapler instrument 10 may further include a spacer block 13 ofa predetermined height disposed at a handle 11 comprising surgicalstapler instrument 10 for defining a predetermined extent handle 11 maybe operated to close a cartridge jaw member and an anvil jaw membercomprising an end effector 20 comprising surgical stapler instrument 10so that said cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other.

In an alternate embodiment of the present invention, a method forselecting a staple cartridge from the standard set of staple cartridges,each containing staples of a predetermined height, optimal for a tissueof a surgical stapling operation comprises steps of: mounting acompression gauge cartridge of the present invention in a cartridge bayof a cartridge jaw member comprising an end effector, together with ananvil jaw member having a tissue contacting surface, of a surgicalstapler instrument; capturing a tissue between said cartridge jaw memberand said anvil jaw member; closing said cartridge jaw member and saidanvil jaw member to compress said tissue captured there-between so thatsaid cartridge jaw member and said anvil jaw member come to apredetermined angular positional relationship with each other; readingout a reactionary load from said compressed tissue displayed on a forcetransducer indicator; providing a reference tissue for which an optimalstaple height for a surgical stapling operation is known; comparing saidreactionary load reading with a reactionary load from said referencetissue compressed so that said cartridge jaw member and said anvil jawmember come to said predetermined angular positional relationship witheach other to determine if said reactionary load is case (1) within,case (2) below or case (3) above a window of a predetermined widtharound said reactionary load from said reference tissue and how large asize of difference is in cases (2) and (3); selecting a staple cartridgefrom the standard set of staple cartridges containing staples of aheight known to be optimal for said reference tissue if the result ofcomparison is case (1), or a staple cartridge containing staples of aheight smaller than that of staples known to be optimal for saidreference tissue taking into account said size of difference if theresult of comparison is case (2), or a staple cartridge containingstaples of a height larger than that of staples known to be optimal forsaid reference tissue taking into account said size of difference if theresult of comparison is case (3). In an alternate embodiment, a methodfor selecting a staple cartridge from the standard set of staplecartridges, each containing staples of a predetermined height, optimalfor a tissue of a surgical stapling operation may further comprise astep of waiting for a predetermined length of time after closing saidcartridge jaw member and said anvil jaw member to compress said tissue.

Referring to FIG. 20, showing a compression gauge cartridge 30 in aperspective view in an embodiment of the present invention, compressiongauge cartridge 30 for use mounted in a cartridge bay of a cartridge jawmember comprising an end effector of a surgical stapler instrument tocompress a tissue and measure a reactionary load therefrom for assistingin selection of a staple cartridge optimal for a tissue of a surgicalstapling operation comprises: a cartridge body 31; and a force gaugeassembly 40, an electronic circuit module 135 including a signalprocessing circuit for conditioning and digitizing a signal from saidforce gauge assembly 40 and wireless transmission circuit, and a batterymodule 136 for providing operational power to said force gauge assembly40 and said electronic circuit module 135 housed in said cartridge body31. In an embodiment, there is provided a corresponding force transducerindicator (not shown in the FIGURE) configured to receive and display awireless signal from compression gauge cartridge 30 indicating theresult of measurement by said force gauge assembly 40. In an embodimentsaid battery module 136 may be of rechargeable type.

Any patent, publication, or other disclosure material, in whole or inpart, that is said to be incorporated by reference herein isincorporated herein only to the extent that the incorporated materialsdoes not conflict with existing definitions, statements, or otherdisclosure material set forth in this disclosure. As such, and to theextent necessary, the disclosure as explicitly set forth hereinsupersedes any conflicting material incorporated herein by reference.Any material, or portion thereof, that is said to be incorporated byreference herein, but which conflicts with existing definitions,statements, or other disclosure material set forth herein will only beincorporated to the extent that no conflict arises between thatincorporated material and the existing disclosure material.

While preferred illustrative embodiments of the invention are describedabove, it will be apparent to those skilled in the art that variouschanges and modifications may be made therein without departing from theinvention. Accordingly, the appended claims should be used to interpretthe scope of the present invention.

What is claimed is:
 1. A surgical compression gauge instrument forcompressing a tissue consistently to a predetermined thickness andmeasure the reactionary load therefrom for assisting selection of staplecartridge and assessing the condition of the tissue comprising: a handleportion; a body portion extending distally from said handle portion anddefining a longitudinal axis; and a tool assembly at the distal end ofand operatively connected to said body portion, said tool assemblycomprising an anvil jaw member having a tissue contacting surface and acompression gauge jaw member having a proximal and distal end, and atissue supporting surface, configured to open and close when operated bysaid handle portion; wherein said compression gauge jaw member comprisesa force gauge assembly, comprising a force transducer and a compressionhead having a tissue compression face, supported by said compressiongauge jaw member positioned between said proximal and distal endthereof; and wherein said compression head is configured and disposed sothat said tissue compression face thereof lies substantially closer tosaid tissue contacting surface of said anvil jaw member than said tissuesupporting surface of said compression gauge jaw member when saidcompression gauge jaw member and said anvil jaw member are in fullyclosed position.
 2. The surgical compression gauge instrument of claim1, wherein said compression gauge jaw member is configured for saidtissue supporting surface to be at least at a predetermined distancefrom said tissue contacting surface of said anvil jaw member when saidcompression gauge jaw member and said anvil jaw member are in fullyclosed position.
 3. The surgical compression gauge instrument of claim2, wherein said tissue supporting surface of said compression gauge jawmember is contoured in such a way to further reduce compression of saidtissue disposed between said tissue supporting surface and said tissuecontacting surface comprising said anvil jaw member when saidcompression gauge jaw member and said anvil jaw member are in a fullyclosed position.
 4. The surgical compression gauge instrument of claim1, wherein said compression gauge jaw member further comprises a spacermember disposed between said tissue contacting surface of said anvil jawmember and said tissue supporting surface of said compression gauge jawmember and proximally with respect to said force gauge assembly.
 5. Thesurgical compression gauge instrument of claim 4, wherein said spacermember is of a rigid construction extending from said tissue supportingsurface of said compression gauge jaw member.
 6. The surgicalcompression gauge instrument of claim 1, wherein said surgicalcompression gauge instrument further comprises a signal conduction meansand a force transducer indicator for bi-directionally conducting asignal from said force transducer to said force transducer indicatordisposed remotely from a surgical site for signal processing and displayand a power and control signals from said force transducer indicatorneeded for operation of said force transducer.
 7. The surgicalcompression gauge instrument of claim 1, wherein said force gaugeassembly comprises said force transducer of a beam type based on astrain gauge.
 8. The surgical compression gauge instrument of claim 1,wherein said force gauge assembly comprises said force transducer of abutton type based on a strain gauge.
 9. The surgical compression gaugeinstrument of claim 1, wherein said force gauge assembly comprises aforce transducer of a planar configuration.
 10. A compression gaugecartridge for use mounted in a compression gauge jaw member comprisingan end effector, together with an anvil jaw member having a tissuecontacting surface, of a surgical compression gauge instrument tomeasure reactionary force from a tissue captured and compressed betweensaid compression gauge and anvil jaw member comprising: a cartridge bodyhaving a proximal end and a distal end, and a tissue supporting surface,a force gauge assembly comprising a force measurement means and acompression head having a tissue compression face, said compression headconfigured to mechanically interface said tissue and said forcemeasurement means, and said force gauge assembly supported by saidcartridge body positioned between said proximal end and said distal endthereof; and wherein said compression head comprising said force gaugeassembly is configured and disposed so that said tissue compression facethereof lies substantially closer to said tissue contacting surface ofsaid anvil jaw member than said tissue supporting surface of saidcartridge body when said compression gauge jaw member and said anvil jawmember are in a fully closed position.
 11. The compression gaugecartridge of claim 10, wherein said cartridge body further comprises aspacer member of a rigid construction extending from said tissuesupporting surface and disposed proximally with respect to said forcegauge assembly.
 12. The compression gauge cartridge of claim 10, whereinsaid cartridge body is configured for said tissue supporting surface tobe at least at a predetermined distance from said tissue contactingsurface of said anvil jaw member when said compression gauge jaw memberand said anvil jaw member are in a fully closed position.
 13. Thecompression gauge cartridge of claim 12, wherein said tissue supportingsurface of said cartridge body is contoured in such a way to furtherreduce compression of said tissue disposed between said tissuesupporting surface and said tissue contacting surface comprising saidanvil jaw member when said compression gauge jaw member and said anviljaw member are in a fully closed position.
 14. The compression gaugecartridge of claim 10, wherein said compression gauge cartridge furthercomprises a signal conduction means and a force transducer indicator forbi-directionally conducting a signal from said force measurement meansto said force measurement means indicator disposed remotely from asurgical site for signal processing and display and a power and controlsignals from said force measurement means indicator needed for operationof said force transducer.
 15. The compression gauge cartridge of claim10, wherein said force gauge assembly comprises said force measurementmeans based on a strain gauge of type selected from the group includinga beam type and a button type.
 16. The compression gauge cartridge ofclaim 10, wherein said force gauge assembly comprises a forcemeasurement means of a planar configuration.
 17. A method forcalibrating a gap distance between a tissue compression face of acompression head comprising a force gauge assembly comprising acompression gauge jaw member and a tissue contacting surface of an anviljaw member comprising an end effector of a surgical compression gaugeinstrument, comprising a spacer member having a anvil contacting face,of the present invention comprising steps of: positioning a referenceblock over the compression head of a height corresponding to apredetermined gap distance between said tissue compression face of saidcompression head and said tissue contacting surface of said anvil jawmember; fully closing said compression gauge jaw member and anvil jawmember; and providing a spacer member of a height corresponding to a gapdistance between said anvil contacting face of said spacer member andsaid tissue contacting surface of said anvil jaw member.